Shojiro Miyake

Electron optical characterization of cubic boron nitride thin films prepared by reactive ion plating

Boron nitride films prepared by reactive ion plating from a boron evaporation source were characterized structurally using three independent electron optical techniques: energy filtered electron diffraction with radial distribution function analysis; electron energy‐loss spectroscopy of the near‐edge structure of the boron K edge; and spectroscopy of the plasmon region of the energy‐loss spectrum. Both specimens had a graded BNx layer between the BN layer and the silicon substrate and in addition one specimen had a titanium bonding layer underneath the BNx layer. The presence of c‐BN in both specimens was confirmed by all techniques. The specimen with the titanium bonding layer was examined in cross section and showed essentially pure c‐BN on the surface. A model for the formation of c‐BN assisted by the compressive stress generated during deposition is proposed.

Micro-Tribological Studies on Fluorinated Carbon Films

Micro-tribology is a key technology in micro-mechanics and the magnetic recording head-media interface. The atomic-scale surface state is very important in micro-tribology. However, the concepts of micro-tribological material design are not clear. The top-surface must be modified to improve micro-tribological properties. To improve adhesion and strength, hard carbon films containing silicon deposited by an electron cyclotron resonance (ECR) plasma depositor are examined for friction and wear using a reciprocating tribometer. Fluorinated silicon-containing films are deposited to reduce atomic-scale wear. Micro-tribological properties of this film are investigated by ultra-low load wear-testing, leading to the following conclusions: (1) The micro-tribological characteristics of silicon-containing carbon film are improved by fluorination. Fluorination decreases the surface energy, evaluated by contact angle to the water, and reduces the micro-wear on an atomic scale. (2) The adhesion to the substrate and the strength of the carbon film are greatly improved by adding small quantities of silicon. These films also have significantly longer lubricating lives.

Microtribological properties and potential applications of hard, lubricating coatings

Abstract Microtribology is a key technology in the information industry. In this field, atomic-scale wear and friction fluctuations degrade equipment performance. New hard, lubricating films seem to be useful in reducing wear and friction fluctuations. This paper discusses a practical surface material composition model that reduces atomic-scale wear (“achieving microtribological zero-wear”). Fluorinated silicon-containing carbon film is suggested for the surface material. The microtribological characteristics of silicon-containing carbon film are improved by fluorination, which reduces the surface energy, atomic-scale wear and friction force fluctuations.

Tribological characteristics of amorphous carbon films investigated by point contact microscopy

Wear marks and frictional force distribution on amorphous carbon films, fluorinated amorphous carbon films, silicon‐containing amorphous carbon films, and fluorinated silicon‐containing amorphous carbon films were investigated by point contact microscopy. Film surfaces were also analyzed by x‐ray photoelectron spectroscopy. The fluorinated silicon‐containing (40%) amorphous carbon film has the highest strength of the tested films. CF4 plasma treatment fluorinated the silicon‐containing (40%) amorphous carbon film, and significantly reduced its frictional coefficient to less than 0.3. The surface of fluorinated silicon‐containing (40%) amorphous carbon film is composed of carbon, silicon, fluorine, and oxygen. Carbon, silicon, and fluorine show the plural chemical states of SiC and CFx. This increases film strength and enhances the lubricating effect of the fluorinated silicon‐containing (40%) amorphous carbon film.

Oriented hydrocarbons transferred from a high performance lubricative amorphous C:H:Si film during sliding in a vacuum

Amorphous C:H containing silicon film shows an extremely low friction coefficient of 0.007 when the film is rubbed with a steel ball in a vacuum. This film is deposited on steel with an electron cyclotron resonance plasma of ethylene and silane. Polarized microinfrared spectroscopy reveals that high lubrication performance is attributed to hydrocarbons transferred from the rubbed film to the ball surface and oriented along the sliding direction.

1 NM DEEP MECHANICAL PROCESSING OF MUSCOVITE MICA BY ATOMIC FORCE MICROSCOPY

Atomic‐scale mechanical processing of layered materials such as muscovite mica was performed using an atomic force microscope (AFM). Processing began at a certain critical load above 130 nN, and the processing depth increased discretely with load. Fracture easily occurred at the two cleavage planes of SiO4–K and K–SiO4 interfaces. With a load slightly larger than the critical load, several repetitions of mechanical sliding of the tip generated a 1 nm deep groove which corresponds to the distance from the top surface of SiO4 to the top surface of the next SiO4 layer beneath it with the removal of residual potassium on the surface. For example, a groove with four steps of 1 nm depth was processed by step‐by‐step mechanical sliding.

Tribological study of cubic boron nitride film

Abstract Tribological properties were measured for cubic boron nitride (c-BN), amorphous boron nitride (a-BN) and hexagonal boron nitride (h-BN) films deposited onto a silicon substrate by a magnetically enhanced plasma ion plating method. The friction and wear properties of the films were measured over a wide range of applied vertical loads: from an ultralight load of 1 μN to 5N.. The tribological properties were highly dependent on the crystal structures. The c-BN film showed the highest wear resistance of the tested films at all loads of microscopic and microscopic sliding. The lubricating performance of the c-BN film also proved to be significant, with a long lubricating life and low friction. It is particularly noted that the c-BN film shows good tribological performance under microscopic sliding, because in microtribology, the physical and chemical properties of surfaces are the primary factors, rather than the mechanical characteristics of the bulk material, as is the case in conventional tribology.

IMPROVED MICROSCRATCH HARDNESS OF ION-PLATED CARBON FILM BY NITROGEN INCLUSION EVALUATED BY ATOMIC FORCE MICROSCOPE

Nitrogen‐containing carbon films where deposited by reactive ion plating under a pure nitrogen ambient. Knoop hardness, microindentation hardness, and microscratch hardness of these films were evaluated. Indentation hardness, such as Knoop hardness and microindentation hardness, is influenced by surface roughness and substrate hardness, so the effect of nitrogen inclusion on the hardness cannot be clearly evaluated. In contrast, an atomic force microscope can clearly evaluate the effect of nitrogen inclusion on scratched wear depth.

Microtribological improvement of carbon film by silicon inclusion and fluorination

In an effort to improve film strength and promote adhesion to the substrate, we used an electron cyclotron resonance (ECR) plasma reactor to deposit carbon films including silicon from an ethylene and silane gas mixture onto silicon substrates. To decrease the atomic interaction between opposing surfaces, carbon surfaces and carbon surfaces including silicon were fluorinated by exposure to CF4 plasma. Silicon inclusion was found to drastically decrease the micro-wear. Moreover, fluorination decreases the surface energy, evaluated by the contact angle to water, and thus reduces microfriction and microwear on an atomic scale.

Wear resistance of C+ -implanted silicon investigated by scanning probe microscopy

Abstract A scanning probe microscope with a very sharp tip was used to investigate the wear resistance of single-crystal silicon and C + -implanted silicon. The C + implantation conditions were 100 keV and 2 × 10 17 ions cm −2 . The C + concentration was analysed using secondary ion mass spectrometry, while the chemical structures of C + -implanted silicon and solid SiC were analysed using X-ray photoelectron spectroscopy. 1. (1) The C + concentration in C + -implanted silicon reached a maximum of 1.5 × 10 22 atoms cm −3 at a depth of 290 nm. 2. (2) Around this 290 nm depth the wear durability of C + -implanted silicon was higher than that of single-crystal silicon. 3. (3) The structure of the region in which the C + concentration was high was similar to that of solid SiC. This structure increases the hardness of the C + -implanted layer and protects against plastic deformation, resulting in a high wear durability for C + -implanted silicon.